Some non-contact imaging devices such as a top-mounted scanner or a digital camera or the like can image not only a two-dimensional object but also an object with a certain thickness, as compared with traditional flatbed scanners. For example, the top-mounted scanner can be used to image a book without separating it into individual pages. However, there may be curved surface deformations in an image of the book obtained by scanning due to limitation of a curved surface imaging pattern. Therefore, a correction model based on upper and lower contours is generally used to correct the curved surface deformations and it is necessary to extract a page boundary of a current page in order to ensure accuracy of a correction result.
Traditional boundary extraction methods typically detect boundaries of an object by tracking a curve having a maximum sum of gradients. However, as shown in FIGS. 1 and 2 for example, for the image obtained by imaging a thick object such as the book using the top-mounted imaging device for example, since there usually exist boundaries of other pages (i.e., noise boundaries) in the vicinity of the boundaries of the current page (i.e., the target boundaries), if a gradient-based method is used to track the page boundaries, the boundaries of other pages may influence accuracy of a result of tracking the boundaries of the current page. Further, gradients of contents near the boundaries of the current page may also influence the accuracy of the result of tracking.